Collet chucks are known from the state of the art in various embodiments.
To hold a tool shank by means of such a collet chuck in a press fit, first, a suitable collet is inserted in the chuck body, the tool receiver of which has an interior diameter suited to the diameter of the tool shank.
The collet, at its external circumference, has an external cone and is inserted into a collet housing of the chuck body, which has a complementary internal cone.
Then that chuck is driven into the chuck body usually with the aid of a clamping nut configured as a sleeve nut. For this purpose, the clamping nut, with its internal thread, is screwed onto a corresponding external thread of the chuck body. In the region of its central opening it comes into contact with the collar of the collet and thus exerts pressure on the collet.
Centering and precise positioning of the collet is achieved essentially by the interaction of the external cone of the collet and the internal cone of the tool chuck. In addition, the contact surfaces of the clamping nut and the collar of the collet contacting each other are usually also conically shaped to achieve a certain centering action also at this point. It has been shown, however, that the strong friction arising during tightening of the clamping nut as the clamping nut interacts with the collet causes problems, when excellent concentricity is to be reproducibly achieved.
To achieve better reproducible concentricity, collet chucks have been suggested in which the clamping nut acts on the collet via a rolling bearing so that such sliding frictional forces with their attendant negative effects would not arise between the clamping nut and the collet during tightening of the clamping nut.
A drawback with this type of collet chucks is that usually the collet and the clamping nut each form a unit so that the collet and the clamping nut cannot be separated from each other with reasonable effort during a tool change. To exchange one collet for a different collet which is needed for clamping the specific tool required, the entire unit consisting of clamping nut and collet must then be exchanged in each case. It is, however, much more cost intensive to have to stockpile diverse units consisting of collet and clamping nut than to simply stockpile various collets.
Due to the above it has already been suggested to design the unit consisting of collet and clamping nut in such a manner that the collet can be disengaged from the clamping nut after complete removal of the clamping nut from the chuck body. However, this takes an unnecessary amount of time during tool change, since it is not sufficient simply to loosen the clamping nut, instead it has to be completely unscrewed.
In view of the above, the problem underlying the invention is to provide a collet chuck in which a quick exchange of only the collet is ensured in spite of the connection of the collet with the clamping nut via a rolling bearing.
The foregoing example of the related art and limitations related therewith are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification and a study of the drawings.